Telephone lines, which are carried by electrical conductors known as tip ring wire pairs, are generally aggregated at a particular point in a building prior to being distributed and connected to various types of telephone equipment, such as, for example, telephones, fax machines, modems etc. As the tip ring pairs generally enter the building as part of a multi-conductor cable, the individual tip ring wire pairs must first be broken out from the cable into individual wire pairs. This is normally accomplished in a junction box known as, for example, a building entrance protector (BEP), or network interface unit (NIU). Within such devices the individual telephone line tip ring pairs are separated from the cable, individually connected to a connector block, and made available for further electrical connection and distribution. Usually there is a protector device inserted between the telephone and central office, or network side of the telephone line and the customer equipment or terminal side of the telephone line to protect the telephone and user, or other equipment connected to the telephone line, from hazardous overvoltages induced in the telephone network or in the cables passing between the telephone central office and the building within which the line is terminated.
In a typical arrangement, the telephone lines coming from the network are first wired to a protector field, which is an array of connectors for receiving the protector device, which is in turn hard wired to a first connector block which provides a first test point for testing the telephone line connections between the building and telephone central office. This first terminal block is hard wired to a multi pair connector, most typically a twenty-five pair connector of the RJ21 type, for further connection to an array of customer bridges which are also hard wired and connectorized via a mating RJ21 connector. The use of a customer bridge permits a subscriber to disconnect terminal equipment from a telephone line so that a subscriber can isolate troubles on the line as originating in the telephone network, or on the terminal equipment side of the telephone line. An example of such an arrangement is shown in U.S. Pat. No. 5,363,440, dated Nov. 8, 1994, the disclosure of which is incorporated herein by reference. U.S. Pat. No. 5,363,440, depicts a multi-layered network interface unit which results in size economies due to the fact that the customer bridge connector block is hingeably connected to the telephone network protector array field so that rather than placing these two arrays side by side they can be mounted in overlying relationship, resulting in a saving of space.
As is often necessary in office buildings or apartment complexes, and other large structures which require multiple items of terminal equipment to be connected to an individual telephone line, there is yet another connector array or field required to effect the distribution of a single telephone line to multiple points within the structure. This is known as either a cross connect or interconnect field, by which a single telephone line is connected to multiple terminal connection points, thereby permitting a single telephone line to be connected to multiple points within the structure. This cross connect field is placed adjacent to the network interface unit of a building entrance protector to facilitate the further distribution of tip ring wire pairs to either a building riser or multiple horizontal ones in a single story structure. Because the cross connect field is generally at least as large as the feeder field, additional wall space must be occupied by the cross connect field. Thus while the use of multi-layered network interface units has resulted in certain amounts of space saving, the necessity for an adjacent cross connect field still requires a significant investment in space when connecting large numbers of telephone lines to multiple points within a building structure.